U.S. patent application number 13/574705 was filed with the patent office on 2013-10-10 for jetless intravenous catheters and mechanical assist devices for hand-injection of contrast media during dynamic tomography and methods of use.
The applicant listed for this patent is Courtney Coursey, Laurens E. Howle, Rendon Nelson, Eli Nichols, Sebastian T. Schinders, Paul W. Weber. Invention is credited to Courtney Coursey, Laurens E. Howle, Rendon Nelson, Eli Nichols, Sebastian T. Schinders, Paul W. Weber.
Application Number | 20130267845 13/574705 |
Document ID | / |
Family ID | 44307232 |
Filed Date | 2013-10-10 |
United States Patent
Application |
20130267845 |
Kind Code |
A1 |
Howle; Laurens E. ; et
al. |
October 10, 2013 |
JETLESS INTRAVENOUS CATHETERS AND MECHANICAL ASSIST DEVICES FOR
HAND-INJECTION OF CONTRAST MEDIA DURING DYNAMIC TOMOGRAPHY AND
METHODS OF USE
Abstract
A jetless intravenous catheter for the delivery of a fluid into
a peripheral vein of a subject includes an elongated body having
proximal and distal ends. The body includes a wall defining an
internal fluid passageway configured to receive fluid flowing in a
longitudinal direction from the proximal end at a first axial
velocity and a tip aperture at the distal end configured to allow
fluid to exit therethrough. The body comprises at least one flow
reducing feature configured to create a laminar-turbulent
transitional flow associated with a fluid flowing in the
longitudinal direction at the first axial velocity and configured
to reduce the flow velocity of fluid exiting the tip to a second
axial velocity that is less than the first axial velocity.
Inventors: |
Howle; Laurens E.; (Mebane,
NC) ; Nelson; Rendon; (Durham, NC) ; Nichols;
Eli; (Durham, NC) ; Schinders; Sebastian T.;
(Bern, CH) ; Coursey; Courtney; (Atlanta, GE)
; Weber; Paul W.; (Vienna, VA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Howle; Laurens E.
Nelson; Rendon
Nichols; Eli
Schinders; Sebastian T.
Coursey; Courtney
Weber; Paul W. |
Mebane
Durham
Durham
Bern
Atlanta
Vienna |
NC
NC
NC
VA |
US
US
US
CH
GE
US |
|
|
Family ID: |
44307232 |
Appl. No.: |
13/574705 |
Filed: |
January 21, 2011 |
PCT Filed: |
January 21, 2011 |
PCT NO: |
PCT/US11/22088 |
371 Date: |
June 17, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61297758 |
Jan 23, 2010 |
|
|
|
61353811 |
Jun 11, 2010 |
|
|
|
Current U.S.
Class: |
600/432 ;
604/118 |
Current CPC
Class: |
A61M 5/14546 20130101;
A61M 25/0068 20130101; A61M 31/005 20130101; A61M 2206/11 20130101;
A61M 2206/20 20130101; A61M 25/007 20130101; A61M 2025/006
20130101; A61M 5/007 20130101; A61M 5/1456 20130101; A61M 2025/0073
20130101 |
Class at
Publication: |
600/432 ;
604/118 |
International
Class: |
A61M 25/00 20060101
A61M025/00; A61M 5/00 20060101 A61M005/00 |
Claims
1. A jetless intravenous catheter for the delivery of a fluid into
a peripheral vein of a subject, comprising: an elongated body
having proximal and distal ends, the body including a wall defining
an internal fluid passageway configured to receive fluid flowing in
a longitudinal direction from the proximal end at a first axial
velocity and a tip aperture at the distal end configured to allow
fluid to exit therethrough; wherein the body comprises at least one
flow reducing feature configured to create a laminar-turbulent
transitional flow associated with a fluid flowing in the
longitudinal direction at the first axial velocity and configured
to reduce the flow velocity of fluid exiting the tip to a second
axial velocity that is less than the first axial velocity; and
wherein the at least one flow reducing feature comprises a
plurality of apertures in the wall such that a portion of a fluid
flowing in the longitudinal direction exits the body through the
plurality of apertures.
2. (canceled)
3. The jetless intravenous catheter of claim 1, wherein the
plurality of apertures comprises a plurality of substantially
circular spaced-apart holes.
4. (canceled)
5. (canceled)
6. The jetless intravenous catheter of claim 3, wherein the
plurality of holes comprises a first row of spaced-apart holes
aligned in the longitudinal direction on a first side of the body
and a second row of spaced-apart holes aligned in the longitudinal
direction on a second, diametrically opposed side of the body.
7. The jetless intravenous catheter of claim 6, wherein the
plurality of holes comprises a third row of spaced-apart holes
aligned in the longitudinal direction on a top side of the
body.
8. The jetless intravenous catheter of claim 6, wherein each of the
first and second rows of holes includes a first hole closest to the
distal end that has a first diameter, a second hole furthest from
the distal end that has a second diameter that is greater than or
less than the first diameter, and a third hole positioned between
the first and second holes that has a third diameter that is
between the first and second diameters.
9. The jetless intravenous catheter of claim 1, wherein the
plurality of apertures comprises a plurality of elongated slits
extending in the longitudinal direction.
10. (canceled)
11. The jetless intravenous catheter of claim 9, wherein the
plurality of slits includes at least one slit on a top of the body
and at least one slit on each of diametrically opposed sides of the
body.
12. The jetless intravenous catheter of claim 11, wherein the
plurality of slits are staggered such that the slit on the top of
the body extends closer to the distal end of the body than the
slits on the diametrically opposed sides of the body.
13. The jetless intravenous catheter of claim 9, wherein each slit
is tapered in the longitudinal direction such that the slit narrows
or widens as the slit extends away from the distal end of the
body.
14. The jetless intravenous catheter of claim 1, wherein the flow
reducing feature is configured to excite the laminar-turbulent
transition instability associated with a fluid flowing in the
longitudinal direction.
15. The jetless intravenous catheter of claim 1, further comprising
a hub connectable to the proximal end of the body, the hub having
an interior cavity with at least one vorticity introducing feature
configured to introduce vorticity to fluid flowing therethrough and
into the fluid passageway of the body.
16. The jetless intravenous catheter of claim 15, wherein the at
least one vorticity introducing feature of the hub comprises at
least one of at least one groove, at least one fin, and at least
one vibrating fin.
17. (canceled)
18. (canceled)
19. The jetless intravenous catheter of claim 1, further comprising
a stylet positioned within the internal fluid passageway, the
stylet having a beveled distal end that extends past the distal end
of the body.
20. (canceled)
21. An intravenous catheter for the delivery of a fluid into a
peripheral vein of a subject, comprising: an elongated body having
proximal and distal ends, the body including a wall defining an
internal fluid passageway configured to receive fluid flowing in a
longitudinal direction from the proximal end and a tip including an
aperture at the distal end configured to allow fluid to exit
therethrough; wherein the body comprises at least one fluid
dispersing feature configured to rapidly disperse a fluid jet
associated with a fluid flowing in the longitudinal direction as
the fluid exits the tip aperture.
22. The intravenous catheter of claim 21, wherein the fluid
dispersing feature comprises an at least partially beveled tip
including an opening toward the top of the body.
23. The intravenous catheter of claim 21, wherein the fluid
dispersing feature comprises at least one groove in an interior of
the wall, the at least one groove helically disposed in the wall
along the longitudinal direction.
24. The intravenous catheter of claim 23, wherein the at least one
groove comprises a plurality of grooves, the grooves configured to
create vorticity in a fluid flowing in the longitudinal
direction.
25. A mechanical assist device for hand-injection of contrast media
during dynamic tomography, comprising: a base; a compartment at a
top of the base sized and configured to securely hold at least a
portion of a syringe; a plate extending upwardly from the top of
the base, the plate sized and configured to receive a plunger of a
syringe securely held in the compartment, the plate slidably
moveable in a first direction from a first position away from the
compartment to a second position adjacent the compartent; and a
hand-operated actuator in communication with the plate, wherein the
plate slidably moves in the first direction in response to
actuation of the actuator; wherein, when a syringe is securely held
in the compartment, the plate slidably moves the plunger of the
syringe from the first position to the second position at a
substantially constant rate such that fluid exits the syringe at a
substantially constant rate in response to actuation of the
actuator.
26. The assist device of claim 25, wherein the base top includes a
slot through which the plate extends and along which the plate
slidably moves in the first direction.
27. The assist device of claim 25, further comprising a monitoring
device for monitoring the rate at which fluid exits the syringe
body.
28-31. (canceled)
32. The assist device of claim 25, wherein a bottom of the base is
configured to be attached to a scanner table.
33. The assist device of claim 25, wherein the device is configured
to deliver at least 125 ml of contrast media at a substantially
constant rate of at least 5 ml/sec.
34. The assist device of claim 33, wherein the contrast media has
an iodine concentration of at least 300 mg/ml.
35. A method for assisting the hand-injection of contrast media
during computer tomography (CT), comprising: (a) providing a
mechanical assist device including: a compartment sized and
configured to securely hold at least a portion of a syringe; a
plate sized and configured to receive a plunger of a syringe
securely held by the compartment, the plate slidably movable in a
first direction from a first position away from the compartment to
a second position adjacent the compartment; and a hand-operated
actuator in communication with the plate such that the plate is
slidable in the first direction in response to actuation of the
actuator; (b) positioning a syringe containing contrast media such
that at least a portion of the syringe is securely held by the
compartment and a plunger of the syringe is received by the plate
in the first position; (c) actuating the actuator to move the plate
and plunger in the first direction; and (d) maintaining a
substantially constant injection rate of contrast media from the
syringe.
36. The method of claim 35, further comprising the following prior
to the actuating step: establishing an intravenous line to a
subject at an injection site; and connecting the syringe to the
intravenous line.
37. The method of claim 36, further comprising placing the subject
on a gantry of a CT scanner.
38. The method of claim 36, further comprising monitoring the
injection site using finger palpation during the actuating
step.
39. The method of claim 35, wherein the maintaining step comprises
monitoring a device configured to monitor media flow.
40. The method of claim 35, wherein the syringe contains a volume
at least 100 ml of contrast media that has an iodine concentration
of at least 300 mg/ml, and wherein the maintaining step comprises
maintaining a constant injection rate of at least 5 ml/sec from the
syringe.
41. (canceled)
Description
RELATED APPLICATIONS
[0001] This application claims priority from U.S. Provisional
Patent Application No. 61/297,758, filed Jan. 23, 2010, and from
U.S. Provisional Patent Application No. 61/353,811, filed Jun. 11,
2010, the disclosures of which are hereby incorporated herein in
their entireties.
FIELD OF THE INVENTION
[0002] This invention relates to intravenous catheters and computer
tomography and, more particularly, to jetless intravenous catheters
and mechanical assist devices for hand-injection of contrast media
during computer tomography, as well as methods of using the
same.
BACKGROUND
[0003] Computer tomography (CT) is a high resolution imaging
technique that has relatively low inherent contrast resolution in
soft tissue structures such as the liver, spleen, pancreas and
kidneys. More than 62 million CT scans are performed each year in
the United States in about 7,200 facilities, and approximately 40
million of these procedures require the intravenous administration
of iodinated contrast material. In order to be effective, the
iodinated contrast material is administered intravenously as a
bolus infusion (not a drip infusion) for most clinical indications.
The exceptions would include the search for acute hemorrhage or
calculi, particularly in the genitourinary tract, when intravenous
contrast material is not necessary and in some cases
contraindicated.
[0004] When administering iodinated contrast material as a bolus,
it is typically delivered via a power injector that is programmed
prior to the CT acquisition. That is, the volume, rate and pressure
of administration are preset before delivering the contrast
material and subsequently acquiring the CT scan. For example, 150
ml of a contrast agent would be administered at 5 ml/sec with a
maximum pressure of 300 pounds per square inch (PSI). However, in
some cases, the use of a power injector results in the
extravasation of the iodinated contrast compound (i.e., leakage
outside the vein into the surrounding soft tissue). Such incidents
result in unreliable and/or ineffective CT scans as well as adverse
effects on the patient, such as skin ulcerations and compartment
syndrome, which require additional medical attention.
[0005] Although some power injectors use devices to detect the
extravasation of contrast material (e.g., EZ-EM, MedRad), the
technologists or nurses responsible for administering the contrast
media bolus frequently encounter a scenario where they are
uncomfortable or wary of using the power injector. Typical
scenarios that may be problematic include: (1) poor or tenuous
intravenous access; (2) use of an existing IV line in an in-patient
that has been in place for several days; (3) injection of a central
venous catheter through which many hospitals have policies
prohibiting power injection; and (4) injection of children. When
one or more of these scenarios occurs, contrast material is
typically administered via a hand injection. That is, the
technologist or nurse administers the contrast material by hand
with one or more syringes. Since the volumes of contrast material
used for CT are typically in the 125-150 ml range, and because
larger volume syringes require more force to push the plunger, the
contrast material is typically divided up into several smaller
syringes. For example, rather than injecting 150 ml of contrast
material via a 150 ml syringe, the technologist or nurse may inject
25 ml through six different 25 ml syringes. This problem is further
exacerbated by the fact that contrast agents with higher
concentrations of iodine (e.g., 370 mg/ml rather than 300 mg/ml)
are becoming increasingly popular in the era of fast, multidetector
CT scanners. The contrast agents with higher concentrations of
iodine have a much higher viscosity, making them even more
difficult to inject by hand. Although administering the bolus via
several small volume syringes is much easier for the individual
performing the injection, the episodic delivery of contrast
material (e.g., inject 25 ml, disconnect the empty syringe,
reconnect a full syringe, inject more contrast material, etc.)
results in a suboptimal vascular and tissue enhancement
profile.
[0006] This administration scheme is not compatible with the goal
of having vivid and sustained vascular and tissue enhancement
during the CT acquisition. As a result, certain subtle but critical
disease processes such as hepatic, pancreatic or renal tumors may
be missed. Furthermore, other protocols such as CT angiography
cannot be performed using a hand injection, since certain
diagnoses, such as pulmonary embolism, rely on very vivid vascular
enhancement. In summary, the use of hand injection reduces the risk
of contrast media extravasation into the perivenous soft tissue but
results in a suboptimal CT scan from a diagnostic standpoint.
[0007] Moreover, the catheters currently used to inject the
contrast media in the patient can cause extravasation. As described
above, because the contrast media must be administered as a bolus,
these catheters produce a jet at the catheter tip, which can result
in extravasation of the contrast media into the surrounding soft
tissue of the patient. For example, vessel wall perforation may be
caused by the contrast media jet exiting the aperture at the tip of
a typical catheter. For this reason, the flow rate of the contrast
media may have to be reduced, requiring a longer time to deliver
the fluid.
[0008] The present disclosure addresses these current problems in
the field of computer tomography imaging.
SUMMARY
[0009] As a first aspect, embodiments of the present invention are
directed to a jetless intravenous catheter for the delivery of a
fluid into a peripheral vein of a subject. The jetless catheter
includes an elongated body having proximal and distal ends. The
body includes a wall defining an internal fluid passageway
configured to receive fluid flowing in a longitudinal direction
from the proximal end at a first axial velocity and a tip aperture
at the distal end configured to allow fluid to exit therethrough.
The body comprises at least one flow reducing feature configured to
create a laminar-turbulent transitional flow associated with a
fluid flowing in the longitudinal direction at the first axial
velocity and configured to reduce the flow velocity of fluid
exiting the tip to a second axial velocity that is less than the
first axial velocity.
[0010] The flow reducing feature may comprise a plurality of
apertures in the wall such that a portion of a fluid flowing in the
longitudinal direction exits the body through the plurality of
apertures.
[0011] In some embodiments, the plurality of apertures may comprise
a plurality of substantially circular spaced-apart holes. The
plurality of holes may be located between about 3 mm and about 10
mm from the distal end. Each of the plurality of holes may have a
diameter of at least about 100 .mu.m.
[0012] The plurality of holes may comprise a first row of
spaced-apart holes aligned in the longitudinal direction on a first
side of the body and a second row of spaced-apart holes aligned in
the longitudinal direction on a second, diametrically opposed side
of the body. The plurality of holes may comprise a third row of
spaced-apart holes aligned in the longitudinal direction on a top
side of the body. Each of the first and second rows of holes may
include a first hole closest to the distal end that has a first
diameter, a second hole furthest from the distal end that has a
second diameter that is greater than or less than the first
diameter, and a third hole positioned between the first and second
holes that has a third diameter that is between the first and
second diameters.
[0013] In some embodiments, the plurality of apertures comprises a
plurality of elongated slits extending in the longitudinal
direction. Each slit may have a length of about 2.5 mm. The
plurality of slits may include at least one slit on a top of the
body and at least one slit on each of diametrically opposed sides
of the body. The plurality of slits may be staggered such that the
slit on the top of the body extends closer to the distal end of the
body than the slits on the diametrically opposed sides of the body.
Each slit may be tapered in the longitudinal direction such that
the slit narrows as the slit extends away from the distal end of
the body.
[0014] The flow reducing feature may be configured to excite the
laminar-turbulent transition instability associated with a fluid
flowing in the longitudinal direction.
[0015] In some embodiments, the jetless catheter includes a hub
connectable to the proximal end of the body, the hub having an
interior cavity with at least one vorticity introducing feature
configured to introduce vorticity to fluid flowing therethrough and
into the fluid passageway of the body. The at least one vorticity
introducing feature of the hub may comprise at least one groove
and/or at least one fin. The at least one vorticity introducing
feature of the hub may comprise at least one vibrating fin.
[0016] In some embodiments, the jetless catheter further comprises
a stylet positioned within the internal fluid passageway, the
stylet having a beveled distal end that extends past the distal end
of the body. The stylet distal end may extend about 2 mm past the
distal end of the body.
[0017] As a second aspect, an intravenous catheter for the delivery
of a fluid into a peripheral vein of a subject includes an
elongated body having proximal and distal ends. The body includes a
wall defining an internal fluid passageway configured to receive
fluid flowing in a longitudinal direction from the proximal end and
a tip including an aperture at the distal end configured to allow
fluid to exit therethrough. The body comprises at least one fluid
dispersing feature configured to rapidly disperse a fluid jet
associated with a fluid flowing in the longitudinal direction as
the fluid exits the tip aperture.
[0018] In some embodiments, the fluid dispersing feature comprises
an at least partially beveled tip including an opening toward the
top of the body. In some embodiments, the fluid dispersing feature
comprises at least one groove in an interior of the wall, the at
least one groove helically disposed in the wall along the
longitudinal direction. The at least one groove may comprise a
plurality of grooves, the grooves configured to create vorticity in
a fluid flowing in the longitudinal direction.
[0019] As a third aspect, a mechanical assist device for
hand-injection of contrast media during dynamic tomography is
provided. The assist device includes a base. A compartment at a top
of the base is sized and configured to securely hold at least a
portion of a syringe. A plate extends upwardly from the top of the
base, and the plate is sized and configured to receive a plunger of
a syringe securely held in the compartment. The plate is slidably
moveable in a first direction from a first position away from the
compartment to a second position adjacent the compartment. A
hand-operated actuator is in communication with the plate, wherein
the plate slidably moves in the first direction in response to
actuation of the actuator. When a syringe is securely held in the
compartment, the plate slidably moves the plunger of the syringe
from the first position to the second position at a substantially
constant rate such that fluid exits the syringe at a substantially
constant rate in response to actuation of the actuator.
[0020] The base top may include a slot through which the plate
extends and along which the plate slidably moves in the first
direction.
[0021] In some embodiments, the assist device comprises a
monitoring device for monitoring the rate at which fluid exits the
syringe body. The monitoring device may be a dial or a digital
display attached to the base.
[0022] The actuator may be a rotatable crank. A drive mechanism may
be provided and configured to convert rotational motion of the
crank into translational motion of the plate such that the plate
slidably moves in the first direction in response to rotation of
the crank.
[0023] In some embodiments, a bottom of the base is configured to
be attached to a scanner table.
[0024] In some embodiments, the assist device is configured to
deliver at least 125 ml of contrast media at a substantially
constant rate of at least 5 ml/sec. In some embodiments, the
contrast media has an iodine concentration of at least 300
mg/ml.
[0025] As a fourth aspect, a method for assisting the
hand-injection of contrast media during computer tomography (CT),
comprises: (a) providing a mechanical assist device including: a
compartment sized and configured to securely hold at least a
portion of a syringe; a plate sized and configured to receive a
plunger of a syringe securely held by the compartment, the plate
slidably movable in a first direction from a first position away
from the compartment to a second position adjacent the compartment;
and a hand-operated actuator in communication with the plate such
that the plate is slidable in the first direction in response to
actuation of the actuator; (b) positioning a syringe containing
contrast media such that at least a portion of the syringe is
securely held by the compartment and a plunger of the syringe is
received by the plate in the first position; (c) actuating the
actuator to move the plate and plunger in the first direction; and
(d) maintaining a substantially constant injection rate of contrast
media from the syringe.
[0026] In some embodiments, the following are the following are
performed prior to the actuating step: (a) establishing an
intravenous line to a subject at an injection site; (b) connecting
the syringe to the intravenous line. In some embodiments, the
method further comprises monitoring the injection site using finger
palpation during the actuating step. The maintaining step may
comprise monitoring a device configured to monitor media flow.
[0027] In some embodiments, the syringe contains a volume at least
100 ml of contrast media that has an iodine concentration of at
least 300 mg/ml, and the maintaining step comprises maintaining a
constant injection rate of at least 5 ml/sec from the syringe.
[0028] As a fifth aspect, an assembly for assisting the rapid hand
injection of contrast media into a peripheral vein of a subject and
minimizing a jet of contrast media into the peripheral vein during
computer tomography is provided. The assembly includes a syringe
having a body, a plunger, and a tip, with the syringe containing at
least 100 ml of contrast media having an iodine concentration of at
least 300 mg/ml. The assembly also includes a mechanical assist
device, comprising: (a) a base; (b) a compartment at a top of the
base sized and configured to securely hold the body of the syringe;
(c) a plate extending upwardly from the top of the base, the plate
sized and configured to receive the plunger of the syringe securely
held in the compartment, the plate slidably moveable in a first
direction from a first position away from the compartment to a
second position adjacent the compartent; and (d) a hand-operated
actuator in communication with the plate, wherein the plate
slidably moves in the first direction in response to actuation of
the actuator. When the syringe body is securely held in the
compartment, the plate slidably moves the plunger of the syringe
from the first position to the second position at a substantially
constant rate such that the contrast media exits the tip of the
syringe at a substantially constant rate of at least 5 ml/sec in
response to actuation of the actuator. The assembly also includes a
catheter in fluid communication with the tip of the syringe, the
catheter comprising: an elongated body having proximal and distal
ends, the body including a wall defining an internal fluid
passageway configured to receive the contrast media flowing from
the syringe tip in a longitudinal direction from the proximal end
at a first axial velocity and a tip aperture at the distal end
configured to allow the contrast media to exit therethrough. The
body comprises at least one flow reducing feature configured to
create a laminar-turbulent transitional flow associated with the
contrast media flowing in the longitudinal direction at the first
axial velocity and configured to reduce the flow velocity of the
contrast media exiting the tip to a second axial velocity that is
less than the first axial velocity.
[0029] It is noted that any one or more aspects or features
described with respect to one embodiment may be incorporated in a
different embodiment although not specifically described relative
thereto. That is, all embodiments and/or features of any embodiment
can be combined in any way and/or combination. Applicant reserves
the right to change any originally filed claim or file any new
claim accordingly, including the right to be able to amend any
originally filed claim to depend from and/or incorporate any
feature of any other claim although not originally claimed in that
manner. These and other objects and/or aspects of the present
invention are explained in detail in the specification set forth
below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 is a perspective view of a mechanical assist device
for hand-injection of contrast media during dynamic computer
tomography according to some embodiments of the invention.
[0031] FIG. 2 is a graph illustrating a pressure injection profile
over time comparing a power injector to hand-injection.
[0032] FIG. 3 is a graph illustrating a time attenuation curve
comparing injections using a power injector, hand injections, and
the device of FIG. 1.
[0033] FIG. 4 is a side cross-section view of a jetless catheter
including at least one flow reducing feature according to some
embodiments.
[0034] FIG. 5 is a perspective view of a portion of the jetless
catheter according to some embodiments having a stylet therethrough
wherein the flow reducing feature comprises holes.
[0035] FIG. 6 is a perspective view of a portion of the jetless
catheter according to some embodiments wherein the flow reducing
feature comprises holes.
[0036] FIG. 7A is a perspective view of a portion of the jetless
catheter according to some embodiments wherein the flow reducing
feature comprises uniform slits.
[0037] FIG. 7B is a perspective view of a portion of the jetless
catheter according to some embodiments wherein the flow reducing
feature comprises staggered uniform slits.
[0038] FIG. 8 is a perspective view of a portion of the jetless
catheter according to some embodiments wherein the flow reducing
feature comprises tapered slits.
[0039] FIG. 9 is a perspective of a portion of a catheter including
a beveled tip according to some embodiments.
[0040] FIG. 10 is a perspective view of a portion of a catheter
including internal spiral grooves according to some
embodiments.
[0041] FIG. 11 is a perspective view of a catheter hub connected to
the catheter of FIG. 7A.
[0042] FIG. 12 is a rear view of the catheter hub and catheter of
FIG. 11.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0043] The present invention will be described more particularly
hereinafter with reference to the accompanying drawings. The
invention is not intended to be limited to the illustrated
embodiments; rather, these embodiments are intended to fully and
completely disclose the invention to those skilled in this art. In
the drawings, like numbers refer to like elements throughout.
Thicknesses and dimensions of some components may be exaggerated
for clarity.
[0044] Well-known functions or constructions may not be described
in detail for brevity and/or clarity.
[0045] Unless otherwise defined, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. The
terminology used in the description of the invention herein is for
the purpose of describing particular embodiments only and is not
intended to be limiting of the invention. As used in the
description of the invention and the appended claims, the singular
forms "a," "an" and "the" are intended to include the plural forms
as well, unless the context clearly indicates otherwise. As used
herein, the term "and/or" includes any and all combinations of one
or more of the associated listed items. Where used, the terms
"attached," "connected," "interconnected," "contacting," "coupled,"
"mounted," "overlying" and the like can mean either direct or
indirect attachment or contact between elements, unless stated
otherwise.
[0046] Referring now to the figures, a mechanical assist device for
the hand-injection of contrast media during dynamic computer
tomography (CT), designated broadly at 10, is illustrated in FIG.
1. The device includes a base 12 having a top 12t. A compartment 14
is attached to or integrally formed with the top 12t of the base
12. The compartment 14 is sized and configured to receive and
securely hold at least a portion of a syringe 16. As illustrated,
the compartment 14 is configured to securely hold a body 16b of the
syringe 16. In various embodiments, the compartment may be
configured to securely hold a syringe having a volume of between
about 100 ml to about 500 ml, between about 110 ml to about 400 ml,
between about 115 ml to about 300 ml, between about 120 ml to about
200 ml, and between about 125 ml to about 175 ml.
[0047] A plate 18 extends upwardly from the top 12t of the base 12.
The plate 18 is sized and configured to receive a plunger 16p of
the syringe 16 (more particularly, the plate 18 may be sized and
configured to receive a plunger handle or head, as illustrated).
The plate 18 is slidably moveable in a first longitudinal direction
D1 from a first position P1 located away from the compartment 14 to
a second position P2 adjacent the compartment 14. As illustrated,
the base top 12t includes a slot 19 through which the plate 18
extends upwardly and along which the plate 18 slidably moves in the
first direction D1. The plate 18 is also slidably moveable in the
opposite longitudinal direction (i.e., from position P2 to position
P1).
[0048] A hand-operated actuator 20 is in communication with the
plate 18. The plate 18 slidably moves in the first direction D1 in
response to actuation of the actuator 20. In the illustrated
embodiment, the actuator 20 is a crank that includes a rotatable
wheel 22 that can be turned by a handle 24. It will be understood
that the actuator 20 may alternatively be a lever or some other
hand-operated actuator.
[0049] In some embodiments, the base 12 can take the form of a
housing, and can include a bottom 12b, opposing side walls 12s, and
opposing end walls 12e. In this regard, the base 12 may include an
at least partially open interior (not visible in FIG. 1), and a
drive mechanism (also not visible) may be positioned therein and
may couple the plate 18 and the actuator 20. For example, the drive
mechanism may convert rotational motion of the crank 20 into
translational motion of the plate 18 such that the plate 18
slidably moves in the first direction D1 responsive to rotation of
the crank 20. The plate 18 may slidably move in the first direction
D1 responsive to rotation of the crank in one direction (e.g.,
counterclockwise), and may slidably move in the opposite direction
responsive to rotation of the crank 20 in the opposite direction
(e.g., clockwise). As will be understood by those of skill in the
art, the drive mechanism may take the form of a rack and pinion, a
jack screw, or the like.
[0050] In operation, the syringe 16 is securely held in the
compartment 14, and the plate 18 slidably moves the plunger 16p in
the first direction D1 from the first position P1 to the second
position P2 in response to actuation of the actuator 20. As the
plunger 16p enters the syringe body 16b, fluid held in the body 16b
is forced therefrom through an aperture 16a at a tip 16t of the
syringe 16. High pressure tubing may be used to connect the tip 16t
to an intravenous (IV) line such as a catheter.
[0051] The actuator 20 provides leverage such that a user can
slidably move the plate 18 from the first position P1 to the second
position P2 at a substantially constant rate and/or a relatively
rapid rate. In this regard, the entire volume or substantially the
entire volume of fluid held in the body of the syringe can exit
therefrom at a substantially constant rate and/or a relatively
rapid rate responsive to actuation of the actuator. In particular,
the device 10 can assist the hand-injection of a relatively large
volume (e.g., at least 100 or 150 ml) of relatively viscous
contrast material (e.g., iopamidol 300 mg iodine/ml or iopamidol
370 mg iodine/ml) at a substantially constant and relatively rapid
rate (e.g., 5 or 10 ml/sec). It will be understood that the device
10 may be used to assist the hand-injection of lesser volumes of
fluid, such as at least 25 ml (a lesser volume may be required for
certain procedures, such as MR). A lower flow rate (e.g., 2 ml/sec)
could also be employed.
[0052] The device 10 may include a monitoring device 26 for
monitoring the pressure or rate at which contrast material exits
the syringe 16. A user may use the monitoring device 26 during
actuation of the actuator 20 to help ensure that the contrast media
is being delivered at a particular rate and/or a substantially
constant rate. The monitoring device 26 may comprise a dial or a
digital display in various embodiments. The device 26 may be
attached to the base 12. Although illustrated as attached to side
12s, the device 26 may be attached to another portion of the base.
Similarly, although the crank 20 is shown attached to one end 12e
of the base, it may be attached to another portion of the base,
such as one of the sides 12s. Moreover, the base bottom 12b may be
configured to be attached to a scanner or a gantry associated with
a scanner.
[0053] The device 10 may provide several advantages. Such
advantages may include: (1) ease of use compared to a single large
syringe or several smaller interchangeable syringes; (2) increased
throughput due to less time preparing for the injection; (3)
increased patient safety since the operator can easily inject the
contrast material and monitor the injection site simultaneously
using finger palpation; (4) significant improvement in the quality
of the CT scan due to markedly improved contrast enhancement
profile; for example, this advantage could translate into improved
detection of solid tumors in solid organs; (5) the potential for
performing more CT protocols that require more demanding contrast
material strategies, such as CT-angiography; (6) the ability to
replace more costly electronic power injectors, particularly in
practices that cannot afford expensive equipment, such as those in
third world countries rural or underserved portions of the U.S.;
and (7) for use as a back-up system, in the event of power
failure.
[0054] Methods for assisting the hand-injection of contrast media
during computer tomography are also contemplated. In one such
operation, the device 10 is provided. The syringe 16 containing
contrast media is positioned such that at least a portion of the
syringe 16 (e.g., the syringe body 16b) is securely held by the
compartment 14 and the syringe plunger 16p is received by the plate
18 in the first position P1. The actuator 20 is actuated to move
the plate 18 and the syringe plunger 16p in the first direction D1.
A constant injection rate of contrast media from the syringe is
maintained.
[0055] In some embodiments, an intravenous (IV) line is established
prior to actuating the actuator. This may be either a new or an
existing IV line. It can be either a peripheral line (e.g.,
antecubital vein in the arm of a subject) or a central line (e.g.,
peripherally inserted central catheter (PICC) or central venous
catheter). The syringe 16 may be removed from the device 10 filled
with the desired contrast media. In some embodiments, the syringe
16 holds a volume of about 150 ml of contrast media, and is
therefore compatible with all concentrations of iodine, even up to
400 mg/ml. This may be advantageous since the more concentrated
agents have a higher viscosity and in some cases are virtually
impossible to administer via a hand injection. For example,
iopamidol 370 mg iodine/ml has only 23% more iodine but has a
viscosity that is almost twice that of iopamidol 300 mg iodine/ml.
Furthermore, the device 10 is also compatible with the pre-filled
syringes which are currently available from the manufacturer (e.g.,
Bracco Diagnostics, Inc.). Syringes pre-filled with contrast
material have the advantage of saving time but generally are a
little more expensive.
[0056] The injection device 10 may be connected to the IV line with
a high pressure tubing of appropriate length and the patient may be
placed on a gantry of a scanner (i.e., when the patient is ready
for acquisition) prior to actuating the actuator and delivering the
contrast media.
[0057] In some embodiments, a constant pressure (PSI) or injection
rate (ml/sec) of contrast media to the patient is established by
monitoring the monitoring device 26.
[0058] Another potential advantage is the ease of use which allows
the user performing the injection to simultaneously monitor the
injection site using finger palpation with their other hand.
Furthermore, in the event of a suspected contrast media
extravasation or if the patient experiences the sudden onset of
nausea and vomiting, the injection can be discontinued immediately
by releasing the crank 20, for example.
[0059] FIG. 2 depicts a pressure profile over time comparing
injections using a power injector versus those administered by
hand. Specifically, the graph shows a pressure profile over time
during the power injection of 150 ml of iopamidol 300 mg iodine/ml
at 2, 3, 4 and 5 ml/sec. Also shown are profile curves for five
different administers (e.g., nurses) performing a hand injection
using five different 30 ml syringes. Note the extreme variation in
enhancement during a hand injection. Also note that during a hand
injection there are intermittent pressures that exceed the pressure
of a power injection at 2 ml/sec.
[0060] In contrast, FIG. 3 shows a time attenuation curve comparing
injections using a power injector, a device according to the
present disclosure, and hand injection. Specifically, FIG. 3 shows
time-attenuation curves for the injection of 150 ml of iopamidol
300 mg iodine/ml at 5 ml/sec. It can be seen that the power
injection curve and the mechanically-assisted hand injection curve
(i.e., using a device similar to the device 10) are very similar.
The hand injection bend has much lower peak enhancement since five
30 ml syringes were used sequentially.
[0061] Turning now to FIGS. 4-12, intravenous catheters that
deliver fluid into a peripheral vein while minimizing or
eliminating a jet from a tip of the catheter are illustrated.
[0062] One potential advantage of a jetless catheter is that when
it delivers fluid into the vein, whether iodinated contrast
material, crystalloids (e.g., normal saline, 5% dextrose in water,
lactated ringers, etc.) or blood products (e.g., whole blood,
packed red blood cells, platelets, etc.), the potential for
extravasation, whereby fluid is deposited outside the lumen of the
vein into the surrounding soft tissue, is reduced. Such
extravasation events can have severe deleterious effects on the
patient, such as skin ulcerations and/or compartment syndrome. The
most devastating severe adverse event is compartment syndrome,
which is associated with a compromise in the blood supply to the
hand, a neurologic deficit in the hand, or both. Severe reactions
often require plastic surgery, either electively or urgently. If an
ulcer develops, a skin graft is typically required on an elective
basis to cover the soft tissue defect. If a compartment syndrome
develops, one or more long incisions are required on an urgent
basis to decompress the tissue. Even if the soft tissue damage is
minor, a significant amount of time and effort is given to the
patient by a physician and the nursing/support staff in order to
prevent a serious injury (e.g., monitoring of pulses and sensation,
elevation of the arm and application of cold compresses) and to
document the event. In addition, in many cases the whole purpose of
administering iodinated contrast material as a bolus is lost,
thereby limiting the diagnostic capability of the scan. Not only is
the bolus of contrast material disrupted but the timing is delayed,
resulting in overall poor vascular and tissue enhancement.
[0063] Another potential advantage of a jetless catheter is that it
may allow for the safe delivery of a higher volume of fluid in a
shorter period of time. Higher flow rates may be advantageous in
patients who have severe fluid depletion such as those in
hemorrhagic shock following trauma. These patients can
significantly benefit from rapid infusion of either crystalloids,
blood products or both. In many patients who experience significant
blood loss following major trauma, rapid fluid infusion may be the
key to their survival. Another clinical scenario where a rapid
intravenous infusion of a fluid substance is advantageous is with
modern multidetector row helical CT scanners. These scanners
acquire a large number of images in a very short period of time
(e.g., the entire abdomen and pelvis in 5 seconds or less), and are
optimized from a diagnostic standpoint when performed following the
administration of intravenous iodinated contrast material. To take
advantage of the speed of the scanners, a bolus of contrast
material must be rapidly administered into a vein, typically
located in the arm. This results in a short but vivid period of
vascular and tissue enhancement and thereby improves the detection
of pathologic processes. Matching scanner speed with rapid contrast
media administration may improve the efficacy of contrast-enhanced
CT in a wide variety of clinical applications. For example, the
detection of highly vascular lesions in the liver or pancreas may
be improved by administering the contrast media at a high rate
during a CT scan. Also, the use of highly concentrated iodinated
contrast material (e.g., 370 mg of iodine/ml vs. 300 mg of
iodine/ml) may further improve this enhancement profile,
particularly during the arterial phase. Contrast media with higher
concentrations of iodine, however, are much more viscous, making
them thick and difficult to inject intravenously. A jetless
catheter according to some embodiments can allow for the very rapid
and safe infusion of even the most viscous iodinated contrast
agents in CT and/or obviate the need for larger caliber angiocaths.
Larger caliber angiocaths are not only more difficult to insert and
establish, but are also more painful to the patients.
[0064] Referring now to FIG. 4, a jetless intravenous catheter 100
is illustrated. The catheter 100 has an elongated body 102 having
opposite proximal and distal ends 102p, 102d. The body 102 includes
a wall 104 defining an internal fluid passageway 106 through which
fluid may flow in a longitudinal direction D2 from the proximal end
102p toward the distal end 102d of the body 102. A tip 107 defines
an aperture 108 located at the body distal end 102d; fluid flowing
through the passageway 106 may exit the body 102 through the tip
aperture 108. As illustrated, the body 102 may include a tapered
section 110 extending from the distal end 102d. The tip 107 forms
at least part of the tapered section 110.
[0065] In some embodiments, the body 102 is constructed of a
polymeric material such as Teflon.TM.. In some embodiments, the
wall 104 has a thickness of about 100 .mu.m, although the wall may
be thinner or thicker in other embodiments. The catheter 100 may be
any suitable size including, but not limited to, calibers of 18, 20
and 22 gauge. These calibers correspond to an internal diameter of
870, 690 and 540 .mu.m, respectively. The catheter length (i.e.,
the length of the body 102 from the proximal end 102p to the distal
end 102d) may be between about 2 cm to about 6 cm, and, in some
embodiments, may be between about 3 cm to about 5 cm. Although
these sizes and lengths match angiocaths that are currently
available, smaller caliber catheters are easier to insert into the
patients and are preferred by nursing staffs. Hence, such catheters
are within the scope of the present disclosure.
[0066] The body 102 includes at least one flow reducing feature
configured to reduce the flow velocity of fluid exiting the tip
aperture. For example, the flow reducing feature may be at least
one aperture 112 in the wall 104 (as illustrated, the flow reducing
feature is a plurality of wall apertures 112). As shown in FIG. 4,
fluid can flow in the longitudinal direction D2 at a first axial
velocity V1 upstream of the wall apertures 112, and the fluid can
exit the tip aperture 108 (i.e., downstream the wall apertures 112)
at a second axial velocity V2 that is less than the first axial
velocity V1.
[0067] Referring to FIG. 5, the catheter 100 is shown having a
stylet 116 inserted therethrough. The stylet 116 may be inserted
through the passageway 106 of the catheter body 102. The sylet 116
is constructed of a rigid material (e.g., stainless steel) to
provide stiffness to the catheter 100 as it is being inserted into
a vein of a subject. In some embodiments, and as illustrated, the
stylet 116 is hollow to allow for the back filling or back flash of
blood which indicates that the distal end 102d of the catheter body
102 is in the lumen of the vein. Also as illustrated, a tip 118 of
the stylet 116 is slant-cut (i.e., beveled) and sharp to facilitate
easy piercing of both the skin and the most superficial wall of the
vein. The stylet 116 has a length such that the sylet 116 extends
about 2 mm beyond the distal end 102d of the catheter body 102.
[0068] Turning back to FIG. 4, the wall apertures 112 may be
clustered relatively close to the distal end 102d of the body 102
to ensure that all the wall apertures 112 are located in a vessel
lumen after insertion into a subject. The position, shape, and size
of the apertures 112 is selected with this in mind, while also
maintaining the structural integrity of the catheter body 102.
Therefore, in various embodiments, the wall apertures 112 are
positioned from about 1 mm to about 12 mm, from about 2 mm to about
11 mm, or from about 3 mm to about 10 mm from the distal end 102d
of the body 102. As will be described below, the wall apertures 112
may be round holes or may be slits, and may be sized, shaped and
positioned so as to not substantially weaken the tensile properties
of the body 102.
[0069] The catheters in accordance with the present disclosure are
for use in intravenous injection of fluids at high injection rates.
As described above catheters incorporate a plurality of apertures
or openings on the catheter wall to allow some portion of the fluid
to escape from the catheters wall, thus reducing the amount and,
therefore, flow speed of fluid exiting the catheter tip. With the
reduced catheter tip flow speed, injections will be less likely to
damage the endothelial wall on the inside of the artery or vein. In
addition, the reduced speed of the tip jet will reduce the
likelihood of a patient experiencing an extravasation event.
[0070] The design of the catheter body 102 allows for the
simultaneous exit of fluid or blood products through a plurality of
different apertures in a distal portion of the body 102. For the
flow conditions present in vivo, the fluid exit pressure (whether
from the tip aperture 108 or the wall aperture 112) will be
identical to the pressure in the vessel. The exit velocity depends
on the difference in pressure between the interior and exterior of
the catheter wall 104 and on the viscous forces opposing the flow.
Each wall aperture 112 is typically smaller than the tip aperture
108, and the viscous forces will be greater for the wall aperture
112 than for the tip aperture 108. Therefore, the fluid exit
velocity for a relatively small wall aperture 112 will be less than
the exit velocity V2 from the catheter tip aperture 108.
Additionally, as some fraction of the flow exits from the wall
apertures 112, the pressure between the interior and exterior of
the catheter wall 104 will decrease toward the more distal region
of the tip. Because the tip pressure difference is less for the
presently disclosed catheter design than for a conventional
catheter without wall apertures, the tip jet will be reduced in
strength. The reduction in tip jet strength or velocity exiting the
tip aperture 108 can result in fewer clinical instances of
extravasation.
[0071] The aperture(s) 112 may take the form of at least one
substantially circular hole 114 or, as illustrated in FIG. 5, a
plurality of substantially circular spaced-apart holes 114. There
may be at least one hole 114 on one or both of diametrically
opposed sides 102s. A through-and-through hole in the wall 104 may
form these diametrically opposed holes 114 (or any other
diametrically opposed apertures disclosed herein) or any
diametrically opposed hole 114 may be formed individually (likewise
for any diametrically opposed aperture disclosed herein).
Alternatively or additionally, there may be at least one hole 114
on a top 102t of the body 102 and at least one hole 114 on a bottom
of the body 102 (not visible) that is diametrically opposed from
the body top 102t. In some embodiments, the top 102t of the body
102 includes holes 114 but no holes are formed in the diametrically
opposed bottom of the body. This configuration may be advantageous
because the bottom of the body 102 may be adjacent a vessel wall
when the body 102 is inserted therein and fluid flowing from one or
more holes on the bottom of the body 102 may therefore impinge on
the vessel wall.
[0072] As used herein, the terms "top," "side," and "bottom" used
in reference to the catheter body 102 are defined as shown in the
figures, and is also with reference to the tabs typically found on
catheter hubs.
[0073] In some embodiments, there may be a longitudinally-arranged
row of spaced-apart holes 114 on one or both of the diametrically
opposed sides 102s of the body 102. In some embodiments, and as
illustrated, there may be a longitudinally-arranged row of
spaced-apart holes 114 on the top 102t of the body 102. At least
some of the rows of holes 114 may be staggered with respect to one
another. For example, the row of holes 114 on the top 102t of the
body 102 may be staggered with respect to the row of holes 114 on
the side 102s of the body 102. In other words, the hole 114 on the
body top 102t closest to the body distal end 102d or tip 107 may be
closer to the distal end 102d or tip 107 than the hole 114 on the
body side 102s closest to the body distal end 102d or tip 107. In
some embodiments, the hole 114 furthest from the distal end 102d or
tip 107 may be located a distance dl that is less than about 12 mm
and, in some embodiments, less than about 10 mm, to help ensure
that no holes 114 are positioned outside the vessel lumen after the
catheter body 102 has been inserted therein.
[0074] Turning to FIG. 6, in some embodiments, holes 114 of varying
diameter can make up a particular row of holes. As illustrated, a
first hole 114.sub.1 closest to the body distal end 102d or tip 107
has a first diameter and a second hole 114.sub.2 furthest from the
distal end 102d or tip 107 has a second diameter that is less than
the first diameter. At least one third hole 114.sub.3 is positioned
between the first and second holes 114.sub.1, 114.sub.2 and has a
third diameter that is between the first and second diameters. In
this configuration, a reduced diameter hole 114 furthest from the
distal end 102d or tip 107 may reduce the likelihood that the hole
will be positioned outside the vessel lumen after insertion into a
vessel. Furthermore, it is contemplated that the hole 114.sub.3 at
the body top 102t can be positioned closer to the distal end 102d
or tip 107 than corresponding holes on the diametrically opposed
sides 102s. This may be accomplished, for example, by staggering
the holes in each respective row and/or by include fewer holes in
the row on the body top 102t. This may be advantageous because the
catheter tip 107 is often directed obliquely or at an angle to the
vessel wall, with the result that the body top 102t does not extend
as far into the vessel lumen as the body sides 102s. It is also
contemplated that the at least some of the holes in a particular
row could have decreasing diameter as they approach the body distal
end 102d or tip 107 in the longitudinal direction (e.g., the
reverse configuration than that shown in FIG. 6).
[0075] In some embodiments, at least some of the holes 114 are at
least about 75 .mu.m in diameter, and, in some embodiments, at
least about 100 .mu.m in diameter, to accommodate both crystalloids
and blood products (red blood cells are about 7 .mu.m, white blood
cells are about 20 .mu.m). The various holes 114 could all be the
same diameter (e.g., uniform holes), or at least some of the holes
114 could have different diameters.
[0076] Turning now to FIG. 7A, in some embodiments, the wall
apertures comprise longitudinally-extending slits 120. As
illustrated, a plurality of slits 120 may be provided with a slit
120 on one or both of the diametrically opposed sides 102s and/or a
slit 120 on the top 102t. A slit 120 may also be included on a
bottom of the body 102 (not visible) that is diametrically opposed
from the top 102t. In some embodiments, the bottom of the body 102
does not include a slit as this surface may reside adjacent a
vessel wall after insertion of the catheter and fluid flowing
therefrom could impinge on the wall.
[0077] In various embodiments, the slits may extend from about 4 mm
to about 12 mm from the body distal end 102d, from about 4 mm to
about 10 mm from the distal end 102d, from about 5 to about 10 mm
from the distal end 102d, or from about 6 mm to about 10 mm from
the distal end 102d. In some embodiments, the slits 120 have a
length of less than 5 mm and extend no further than 10 mm from the
distal end 102d of the body 102. Terminating the slits 120 at less
than about 12 mm or less than about 10 mm from the distal end can
help ensure that the slits are located within a vessel lumen after
the catheter has been inserted therein. In various embodiments, the
slits have a width of less than 100 .mu.m, less than 50 .mu.m, and
less than 25 .mu.m.
[0078] Turning to FIG. 7B, a slit 120t located on the body top 102t
can be staggered relative to slits 120s located on the
diametrically opposed body sides 120s. In this regard, the slit
120t terminates at a point that is closer the distal end 102d or
tip 107 than the slits 120s. Again, catheters are often inserted at
an angle to the vessel wall such that the top 102t does not extend
as far into the vessel lumen as the diametrically opposed sides
102s. Thus, this configuration helps ensure that the slit 120t
associated with the top 102t does not extend outside the vessel
lumen. This potential advantage can also be realized by providing a
slit on the top 102t that is not as long as those on the
diametrically opposed sides 102s such that the slit on the top 102t
terminates a lesser distance from the distal end of the body 102d
or tip 107. Other staggered slit configurations are contemplated;
for example, a slit on the top 102t could terminate at a point that
is further from the distal end 102d or tip 107 than the slits on
the sides 102s.
[0079] Referring now to FIG. 8, tapered slits may be provided. In
this regard, a slit 130 can have a first end 132 closest to the
distal end 102d that is wider than a second end 134 furthest from
the distal end 102d or tip 107. The slits may also widen as they
extend away from the distal end 102d or tip 107 (i.e., the reverse
configuration from that shown in FIG. 8). It is contemplated that
the embodiments shown in FIGS. 7B and 8 can be combined; that is,
the flow reducing feature could comprise tapered slots that are
staggered with respect to one another
[0080] The presence of wall apertures may reduce the volumetric
flow from the catheter tip aperture. In some embodiments, the
spacing between the wall apertures and the shape of the wall
apertures are such that the disturbance created by these apertures
on the flow within center of the catheter (i.e., fluid flowing in
the longitudinal direction through the passageway 106 from the
proximal end 102p as shown in FIG. 4) will create a
laminar-to-turbulent transition and/or destabilize the flow. The
destabilized axial flow can more readily overcome the large
momentum of the high velocity catheter flow and therefore more
readily exit the wall apertures. In addition, the destabilized flow
may mix more easily once it leaves the catheter. Without being
bound by theory, in some embodiments, the wall apertures are
configured to excite the Tollmien-Schlichting instability
associated with the fluid flowing through the passageway 106.
[0081] Catheters with longitudinal slits or openings in the
sidewalls have been described, for example, in U.S. Pat. Nos.
5,250,034 to Appling et al. and 5,857,464 to Desai, the disclosures
of which are incorporated herein in their entireties. However, the
slits or openings are not arranged so as to create a
laminar-to-turbulent transition.
[0082] In contrast, the catheters described herein include features
(e.g., wall apertures) arranged to destabilize the fluid. For
example, the features may create a laminar-to-turbulent
transitional flow instability, create a Reynolds instability,
excite the Tollmien-Schlichting instability associated with the
fluid, and/or create any other flow instability. As a result, the
maximum velocity occurs inside the catheter itself, and more
particularly upstream of the wall apertures, as opposed to
occurring at the tip aperture. This is shown schematically in FIG.
4, with the upstream velocity V1 being greater than the downstream
velocity V2. Accordingly, the maximum fluid velocity is not
impinging on the vessel wall. Indeed, the addition of side holes
and side slits to standard angiocatheters in the configurations
described herein experimentally resulted in a plume rather than a
jet of contrast material exiting the catheter tip.
[0083] Furthermore, standard catheters direct all of the shear
stress onto the wall region adjacent to the tip, whereas the
catheters with wall apertures arranged in the manner disclosed
herein spread out the higher shear stress regions, with the fluid
flowing from the wall apertures producing smaller, localized shear
stress regions. In other words, the higher shear stress region
produced by the tip is diminished by the disclosed configurations
of the wall apertures which create instability such that the high
momentum axial flow can be overcome and permit a portion of the
fluid to exit the wall apertures. This may be especially true where
high flow rates and/or highly viscous fluids are employed, such as
with contrast media used in modern computer tomography
techniques.
[0084] In some embodiments, catheters for use in the injection of
fluids with tip shapes that disperse the fluid exit jet are
provided. Again, when fluids are injected into patients at high
rates, such as during the administration of contrast enhancing
media for CT or MR imaging studies, the fluids can exit the
catheter tip at high velocities. There is a possibility that the
fluid leaving the tip at a high velocity could impinge upon the
interior vessel wall and cause injury or extravasation. In
accordance with some embodiments, and as shown in FIG. 9, catheters
with non-axis symmetric tip geometries may be designed to rapidly
disperse the jet once the fluid exits the catheter tip.
[0085] The tip 140 illustrated in FIG. 9 is beveled such that flow
of a fluid therethrough is dispersed between a closed bottom
portion 142 and an inwardly and upwardly extending open portion
144. Once a catheter has been inserted past a first vessel wall,
the catheter tip is often adjacent the opposite wall inside the
vessel lumen. The configuration of the tip 142 may reduce
impingement and shear stress against the adjacent vessel wall
because the flow is urged upward away from the wall and is more
readily dispersed. It is contemplated that the tip configuration
shown in FIG. 9 may be advantageously combined with the flow
reducing features described herein to further minimize impingement
against a vessel wall and to further reduce shear stress at the
wall.
[0086] In some embodiments, and as shown in FIG. 10, a catheter
comprises internal spiral grooves 150. The grooves 150 may be
formed in an interior of the wall and may be helically disposed in
the longitudinal direction. The internal grooves 150 are configured
to create a vortical flow in the injected medium. This vortical
flow causes the medium to disperse rapidly once it exits the tip of
the catheter. Since the medium disperses rapidly after leaving the
catheter tip, it may cause less vessel wall damage or lessen the
possibility of extravasation. It is contemplated that the spiral
grooves 150 could be advantageously employed with other embodiments
described herein. For example, the spiral grooves 150 could be
employed upstream and/or downstream of the flow reducing features
described above to further encourage the laminar-to-turbulent
transition flow and encourage fluid flow out of the wall apertures
and/or to encourage fluid dispersion at the tip.
[0087] Referring now to FIGS. 11 and 12, a catheter hub 200 is
connectable to the catheter body proximal end 102p. The hub 200 has
an interior cavity 202 through which fluid may flow into the
catheter body at the proximal end 102p. The interior cavity 202
includes at least one vorticity introducing feature therein that is
configured to introduce vorticity to fluid flowing through the
interior cavity 202 and into the catheter body. The vorticity
introducing feature can comprise at least one groove or at least
one fin, for example. As illustrated, the vorticity introducing
feature comprises a plurality of fins 204 designed to introduce
vorticity to the flow of the fluid through the catheter of the
body. In certain embodiments, the hub 200 accompanies previous
catheter designs described herein containing different arrangements
of holes and slits near the tip of the catheter. For example, as
illustrated in FIG. 11, the hub 200 can be used in combination with
a catheter 100 including a plurality of longitudinally-extending
slits 120. However, any suitable catheter, including the catheters
illustrated in FIGS. 4-10, may also be used. The vorticity
increases the amount of fluid that escapes from the side holes and
slits, further reducing the stress applied to the blood vessel and
decreasing the likelihood of an extravasation event.
[0088] In some embodiments, the fins 204 vibrate to cause a
disturbance in the flow. In such embodiments, the fins 204 may have
geometrical and material properties such that their resonant
frequency is matched by the desired flow rate. The hub 200 can be
used in combination with any suitable catheter, including one of
the previous catheter designs described herein with an arrangement
of holes and slits in the catheter body, thereby increasing the
amount of fluid that exits the catheter through the side holes and
slits.
[0089] Another aspect of the present disclosure provides a method
for high-frequency (e.g., greater than 1 Hz) periodic modulation of
injection pressure and flow rate. The high-frequency modulation is
designed to destabilize the flow of the injected medium by
encouraging laminar-to-turbulent flow. The high-frequency
modulations may take place either due to mechanical or acoustic
forcing at the mechanical injector or at any point in the flow
circuit external to the patient. In some embodiments, this
modulation is paired with flow circuit hardware specifically tuned
to resonate at the driving frequency. This may further enhance
instability in the flow and cause the medium to disperse more
quickly once it exits the catheter tip.
[0090] Notably, the catheters in some embodiments do not contain
any flaps to vibrate or dislodge, and the catheters do not change
shape following insertion as a result of heat or during the
injection of fluid as a result of pressure or fluid shearing force.
Moreover, in some embodiments, the removal of the stylet after
intravenous access reveals the end hole as well as the multiple
wall apertures that are positioned such that the catheter will only
need to enter the vein a total of about 10 mm to ensure that all of
the side holes are within the lumen.
[0091] Also within the scope of the present disclosure is a laser
machining process for creating the wall apertures in intravenous
catheters. A laser machining process for beveling catheter tips is
described in U.S. Pat. No. 5,425,803 to van Schravendijk et al.
However, the laser machining process according to the present
disclosure involves the creation of a plurality of wall apertures
in catheter walls with a geometric arrangement such at that the
openings encourage destabilized flow and/or create
laminar-to-turbulent transitional flow.
[0092] According to some embodiments of the present invention, an
assembly for assisting the rapid hand injection of contrast media
into a peripheral vein of a subject and minimizing a jet of
contrast media into the peripheral vein during computer tomography
is provided. In some embodiments, the assembly includes the
mechanically-assisted hand injection device 10 depicted in FIG. 1
and also includes one of the catheters described in the present
application. A syringe (16, FIG. 1) may also be included, with the
syringe tip 16t in communication with the catheter. High-pressure
tubing may be used to connect the syringe tip 16t to the
catheter.
[0093] The foregoing is illustrative of the present invention and
is not to be construed as limiting thereof. Although exemplary
embodiments of this invention have been described, those skilled in
the art will readily appreciate that many modifications are
possible in the exemplary embodiments without materially departing
from the novel teachings and advantages of this invention.
Accordingly, all such modifications are intended to be included
within the scope of this invention as defined in the claims. The
invention is defined by the following claims, with equivalents of
the claims to be included therein.
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